A normal woman's menstrual cycle has three general phases, namely, 1) a phase when the woman experiences menstrual bleeding; 2) a phase when a woman discharges cervical mucus and ovulates; and 3) a phase when the ovulated egg has died and the cervical mucus has dried up. In phase 1 (the menses phase), the woman is in a phase of unlikely fertility. When the woman is in phase 2 (the fertile phase), the woman is in a phase of possible fertility. When the woman is in phase 3 (the infertile phase), the woman is in a phase of complete infertility.
There are a number of natural family planning systems that have been developed and are being used successfully by women and couples. However, there are limitations methodologically and educationally to each of these systems. Despite the availability of existing natural family planning systems, only 2 percent of couples in the United States and 5 percent world wide use natural means of birth regulation. In this context, there is a need for more “user friendly” systems that reflect current scientific evidence in regard to natural family planning and present the continuum of natural family planning use.
Existing sympto-thermal systems integrate mucus observations with post-ovulatory temperature changes. However, recent studies suggest that the correlation of biphasic temperature changes to ovulation is accurate in only 70 percent of cases. Sympto-thermal methods are also dependent upon written literacy in which women are able to comfortably read a thermometer, chart temperatures and interpret the temperature pattern. This level of written literacy may be difficult to achieve in many areas of the world, effectively precluding sympto-thermal NFP system use.
Existing ovulation methods rely solely on mucus observations and interpretations. In this way, they can be accessible to both literate and non-literate users. However existing mucus only methods are based upon data that may not accurately reflect day specific pregnancy probabilities. By recommending abstinence during vaginal bleeding and emphasizing the use of “dry days” before ovulation, such methods may increase surprise pregnancy rates. Such pre-ovulatory surprise pregnancy rates have been documented in the World Health Organization data that examined ovulation method effectiveness.
A recently developed method of natural family planning (The Standard Days Method) holds promise as a simplified method of fertility awareness. While the method relies on day-specific pregnancy probabilities, it is limited to use in women with regular cycles from 26 to 32 days.
Finally, there is a need to make natural family planning relevant culturally and generationally. Within the United States and Europe, there is interest in natural, non-hormonal and non-invasive means of medical and reproductive health care. At the same time, women and couples of reproductive age, have grown up accustomed to technological interventions and instrumentations as a part of every day life. Meanwhile, in the developing world, women and couples may have a wide range of educational backgrounds. For example, in Africa as a whole, only 40 percent of women are considered literate. In the context of widespread illiteracy, there is a need for family planning systems that are simple, visual and can be used by all women and couples, regardless of their educational background.